Nevertheless, some philosophers, like Descartes, continued to argue against the existence of empty space until the scientific discovery of a physical vacuum.
A typical response of this type is voiced by the Venetian Giacomo Casanova (1725–1798) in conversation with his landlord, one Dr. Gozzi, who also happens to be a priest: As everything, for him, was an article of faith, nothing, to his mind, was difficult to understand: the Great Flood had covered the entire world; before, men had the misfortune of living a thousand years; God conversed with them; Noah had taken one hundred years to build the ark; while the earth, suspended in air, stood firmly at the center of the universe that God had created out of nothingness.
In philosophy, to avoid linguistic traps over the meaning of "nothing", a phrase such as not-being is often employed to make clear what is being discussed.
[9] On the death of his friend Michele Besso, Einstein consoled his widow with the words, "Now he has departed from this strange world a little ahead of me.
"[10] Leucippus (early 5th century BC), one of the atomists, along with other philosophers of his time, made attempts to reconcile this monism with the everyday observation of motion and change.
These are the invisibly small "atoms" of Greek atomist theory, later expanded by Democritus (c. 460–370 BC), which allows the void to "exist" between them.
Bertrand Russell points out that this does not exactly defeat the argument of Parmenides but, rather, ignores it by taking the rather modern scientific position of starting with the observed data (motion, etc.)
[11] Cyril Bailey notes that Leucippus is the first to say that a "thing" (the void) might be real without being a body and points out the irony that this comes from a materialistic atomist.
[15] The idea that space can actually be empty was generally still not accepted by philosophers who invoked arguments similar to the plenum reasoning.
Although Descartes’ views on this were challenged by Blaise Pascal, he declined to overturn the traditional belief, horror vacui, commonly stated as "nature abhors a vacuum".
This remained so until Evangelista Torricelli invented the barometer in 1643 and showed that an empty space appeared if the mercury tube was turned upside down.
Even Torricelli's teacher, Galileo Galilei, had previously been unable to adequately explain the sucking action of a pump.
[16] John the Scot, or Johannes Scotus Eriugena (c. 815–877) held many surprisingly heretical beliefs for the time he lived in for which no action appears ever to have been taken against him.
For instance, Śūnyatā (emptiness), unlike "nothingness", is considered to be a state of mind in some forms of Buddhism (see Nirvana, mu, and Bodhi).
Some authors have pointed to similarities between the Buddhist conception of nothingness and the ideas of Martin Heidegger and existentialists like Sartre,[22][23] although this connection has not been explicitly made by the philosophers themselves.
In some Eastern philosophies, the concept of "nothingness" is characterized by an egoless state of being in which one fully realizes one's own small part in the cosmos.
In Taoist philosophy, however real this world is, its main characteristic is impermanence, whereas the Tao has a permanence that cannot be described, predetermined, or named.
Despite the proven existence of vacuum, scientists through the 17th to 19th centuries thought there must be a medium pervading all space that allowed the transmission of light or gravity.
[25] Proof that light has a wave nature, rather than Newton's corpuscles, was provided by Thomas Young in his 1803 interference experiment, seemingly confirming the need for an aether.
[26] The most well known attempt to detect the existence of the aether was conducted by Albert A. Michelson in an experiment of 1881, later repeated with Edward W. Morley in 1887 with more precision.
This failed to show the desired effect, but reluctant to abandon the aether theory, various attempts were made to modify it to account for the Michelson-Morley result.
[27][28] Finally, Albert Einstein, building on the work of Hendrik Lorentz, published his theory of special relativity in 1905 which dispenses entirely with the need for a luminiferous aether to explain the transmission of light.
First proposed by Paul Dirac in 1927, the lowest energy state has constant random vacuum fluctuations which bring into existence short-lived virtual particles.